Vulnerability-Lookup

FKIE_CVE-2025-39927

Vulnerability from fkie_nvd - Published: 2025-10-01 08:15 - Updated: 2026-10-21 13:18

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.7 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: ceph: fix race condition validating r_parent before applying state Add validation to ensure the cached parent directory inode matches the directory info in MDS replies. This prevents client-side race conditions where concurrent operations (e.g. rename) cause r_parent to become stale between request initiation and reply processing, which could lead to applying state changes to incorrect directory inodes. [ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to move CEPH_CAP_PIN reference when r_parent is updated: When the parent directory lock is not held, req->r_parent can become stale and is updated to point to the correct inode. However, the associated CEPH_CAP_PIN reference was not being adjusted. The CEPH_CAP_PIN is a reference on an inode that is tracked for accounting purposes. Moving this pin is important to keep the accounting balanced. When the pin was not moved from the old parent to the new one, it created two problems: The reference on the old, stale parent was never released, causing a reference leak. A reference for the new parent was never acquired, creating the risk of a reference underflow later in ceph_mdsc_release_request(). This patch corrects the logic by releasing the pin from the old parent and acquiring it for the new parent when r_parent is switched. This ensures reference accounting stays balanced. ]

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/15f519e9f883b316d86e2bb6b767a023aafd9d83	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2bfe45987eb346e299d9f763f9cd05f77011519f	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/db378e6f83ec705c6091c65d482d555edc2b0a72	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/dc5aad078abc416dd3d555c50f5308c16ba918a7

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	2.6.34
linux	linux_kernel	2.6.34
linux	linux_kernel	2.6.34
linux	linux_kernel	2.6.34
linux	linux_kernel	2.6.34
linux	linux_kernel	2.6.34
linux	linux_kernel	2.6.34
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ceph/debugfs.c",
            "fs/ceph/dir.c",
            "fs/ceph/file.c",
            "fs/ceph/inode.c",
            "fs/ceph/mds_client.c",
            "fs/ceph/mds_client.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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            "fs/ceph/file.c",
            "fs/ceph/inode.c",
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            "fs/ceph/mds_client.h"
          ],
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          "vendor": "Linux",
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              "status": "affected",
              "version": "2.6.34"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.12.48",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.16.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix race condition validating r_parent before applying state\n\nAdd validation to ensure the cached parent directory inode matches the\ndirectory info in MDS replies. This prevents client-side race conditions\nwhere concurrent operations (e.g. rename) cause r_parent to become stale\nbetween request initiation and reply processing, which could lead to\napplying state changes to incorrect directory inodes.\n\n[ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to\n  move CEPH_CAP_PIN reference when r_parent is updated:\n\n  When the parent directory lock is not held, req-\u003er_parent can become\n  stale and is updated to point to the correct inode.  However, the\n  associated CEPH_CAP_PIN reference was not being adjusted.  The\n  CEPH_CAP_PIN is a reference on an inode that is tracked for\n  accounting purposes.  Moving this pin is important to keep the\n  accounting balanced. When the pin was not moved from the old parent\n  to the new one, it created two problems: The reference on the old,\n  stale parent was never released, causing a reference leak.\n  A reference for the new parent was never acquired, creating the risk\n  of a reference underflow later in ceph_mdsc_release_request().  This\n  patch corrects the logic by releasing the pin from the old parent and\n  acquiring it for the new parent when r_parent is switched.  This\n  ensures reference accounting stays balanced. ]"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nceph: corregir condici\u00f3n de carrera al validar r_parent antes de aplicar el estado\n\nA\u00f1adir validaci\u00f3n para asegurar que el inodo del directorio padre en cach\u00e9 coincide con la informaci\u00f3n del directorio en las respuestas de MDS. Esto previene condiciones de carrera del lado del cliente donde operaciones concurrentes (p. ej., renombrar) hacen que r_parent quede obsoleto entre el inicio de la solicitud y el procesamiento de la respuesta, lo que podr\u00eda llevar a aplicar cambios de estado a inodos de directorio incorrectos.\n\n[ idryomov: incorpor\u00f3 una correcci\u00f3n de kerneldoc y una correcci\u00f3n de seguimiento de Alex para mover la referencia CEPH_CAP_PIN cuando r_parent se actualiza:\n\nCuando el bloqueo del directorio padre no est\u00e1 retenido, req-\u003er_parent puede quedar obsoleto y se actualiza para apuntar al inodo correcto. Sin embargo, la referencia CEPH_CAP_PIN asociada no se estaba ajustando. El CEPH_CAP_PIN es una referencia en un inodo que se rastrea con fines contables. Mover este pin es importante para mantener la contabilidad equilibrada. Cuando el pin no se mov\u00eda del padre antiguo al nuevo, creaba dos problemas: La referencia en el padre antiguo y obsoleto nunca se liberaba, causando una fuga de referencias. Nunca se adquir\u00eda una referencia para el nuevo padre, creando el riesgo de un desbordamiento negativo de referencias m\u00e1s tarde en ceph_mdsc_release_request(). Este parche corrige la l\u00f3gica liberando el pin del padre antiguo y adquiri\u00e9ndolo para el nuevo padre cuando se cambia r_parent. Esto asegura que la contabilidad de referencias se mantenga equilibrada. ]"
    }
  ],
  "id": "CVE-2025-39927",
  "lastModified": "2026-10-21T13:18:16.970",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
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        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
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          "availabilityImpact": "HIGH",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
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        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
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          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
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        "exploitabilityScore": 1.0,
        "impactScore": 3.6,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
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          "options": [
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              "exploitation": "none"
            },
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              "automatable": "no"
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            {
              "technicalImpact": "partial"
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          "role": "CISA Coordinator",
          "timestamp": "2026-01-14T17:39:17.680672Z",
          "version": "2.0.3"
        }
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  "published": "2025-10-01T08:15:36.097",
  "references": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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    },
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-362"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-362"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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  ]
}

CVE-2025-39927 (GCVE-0-2025-39927)

Vulnerability from cvelistv5 – Published: 2025-10-01 08:07 – Updated: 2026-10-21 12:37

Title

ceph: fix race condition validating r_parent before applying state

Summary

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

4.7 (Medium)


                        
                          CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-01-14 17:39 UTC

CWE

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7033 records in the last 180 days details

References

4 references

URL	Tags
https://git.kernel.org/stable/c/dc5aad078abc416dd…
https://git.kernel.org/stable/c/db378e6f83ec705c6…
https://git.kernel.org/stable/c/2bfe45987eb346e29…
https://git.kernel.org/stable/c/15f519e9f883b316d…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 9030aaf9bf0a1eee47a154c316c789e959638b0f , < dc5aad078abc416dd3d555c50f5308c16ba918a7 (git) Affected: 9030aaf9bf0a1eee47a154c316c789e959638b0f , < db378e6f83ec705c6091c65d482d555edc2b0a72 (git) Affected: 9030aaf9bf0a1eee47a154c316c789e959638b0f , < 2bfe45987eb346e299d9f763f9cd05f77011519f (git) Affected: 9030aaf9bf0a1eee47a154c316c789e959638b0f , < 15f519e9f883b316d86e2bb6b767a023aafd9d83 (git)
Linux	Linux	Affected: 2.6.34 Unaffected: 0 , < 2.6.34 (semver) Unaffected: 6.6.160 , ≤ 6.6.* (semver) Unaffected: 6.12.48 , ≤ 6.12.* (semver) Unaffected: 6.16.8 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "HIGH",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 4.7,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2025-39927",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-01-14T17:39:17.680672Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-362",
                "description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-01-14T17:42:45.563Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ceph/debugfs.c",
            "fs/ceph/dir.c",
            "fs/ceph/file.c",
            "fs/ceph/inode.c",
            "fs/ceph/mds_client.c",
            "fs/ceph/mds_client.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "dc5aad078abc416dd3d555c50f5308c16ba918a7",
              "status": "affected",
              "version": "9030aaf9bf0a1eee47a154c316c789e959638b0f",
              "versionType": "git"
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              "versionType": "git"
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          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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            "fs/ceph/dir.c",
            "fs/ceph/file.c",
            "fs/ceph/inode.c",
            "fs/ceph/mds_client.c",
            "fs/ceph/mds_client.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.34"
            },
            {
              "lessThan": "2.6.34",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.48",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "2.6.34",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.48",
                  "versionStartIncluding": "2.6.34",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16.8",
                  "versionStartIncluding": "2.6.34",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "2.6.34",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix race condition validating r_parent before applying state\n\nAdd validation to ensure the cached parent directory inode matches the\ndirectory info in MDS replies. This prevents client-side race conditions\nwhere concurrent operations (e.g. rename) cause r_parent to become stale\nbetween request initiation and reply processing, which could lead to\napplying state changes to incorrect directory inodes.\n\n[ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to\n  move CEPH_CAP_PIN reference when r_parent is updated:\n\n  When the parent directory lock is not held, req-\u003er_parent can become\n  stale and is updated to point to the correct inode.  However, the\n  associated CEPH_CAP_PIN reference was not being adjusted.  The\n  CEPH_CAP_PIN is a reference on an inode that is tracked for\n  accounting purposes.  Moving this pin is important to keep the\n  accounting balanced. When the pin was not moved from the old parent\n  to the new one, it created two problems: The reference on the old,\n  stale parent was never released, causing a reference leak.\n  A reference for the new parent was never acquired, creating the risk\n  of a reference underflow later in ceph_mdsc_release_request().  This\n  patch corrects the logic by releasing the pin from the old parent and\n  acquiring it for the new parent when r_parent is switched.  This\n  ensures reference accounting stays balanced. ]"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The race is created entirely by concurrent local syscalls (path lookup driving `ceph_d_revalidate()` and `rename()`) on a mounted CephFS; no network-facing listener is involved, as the kernel here is the client consuming replies from its trusted MDS.\nAC:L - The attacker controls both sides of the race \u2014 one thread forces LOOKUP requests via lease-expired path walks, another repeatedly renames the target dentry between directories \u2014 and can retry indefinitely with no cost or side effects until the window is hit.\nPR:L - Only an unprivileged local account with access to the CephFS mount is needed; `ceph_d_revalidate()` sets `r_parent` without `CEPH_MDS_R_PARENT_LOCKED` on every ordinary path walk, and `rename()` within the attacker\u0027s own directories suffices to win the race.\nUI:N - The attacker\u0027s own two threads supply both the request and the concurrent rename; no action by any other user or administrator is required beyond the CephFS mount already existing.\nS:U - The corruption is confined to the kernel\u0027s own inode/cap/dcache state within the same security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - `ceph_fill_inode()` copies the foreign directory\u0027s mode, uid/gid, nlink, size, times, and its entire xattr blob (including security labels) onto an inode the attacker can then `stat`/`getxattr`, and the phantom caps installed by `ceph_add_cap()` make the client serve that stolen metadata indefinitely without revalidation.\nI:H - Ownership and permission bits of a directory inode are overwritten with another directory\u0027s values (e.g. an attacker-owned 0777 mode landing on a root-owned 0700 directory), and cap ids, snaprealm membership, and the dir-complete/empty flag are all corrupted, subverting the client\u0027s permission and consistency model.\nA:H - The cap id written by `ceph_add_cap()` no longer matches what the MDS issued for that inode, so cap flushes are rejected and threads block indefinitely on `i_cap_wq` (fsync/sync/umount hangs), while wrongly setting dir-complete with `i_size_write(inode, 0)` makes a live directory\u0027s entries unreachable for all users on the client."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:37:35.623Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/dc5aad078abc416dd3d555c50f5308c16ba918a7"
        },
        {
          "url": "https://git.kernel.org/stable/c/db378e6f83ec705c6091c65d482d555edc2b0a72"
        },
        {
          "url": "https://git.kernel.org/stable/c/2bfe45987eb346e299d9f763f9cd05f77011519f"
        },
        {
          "url": "https://git.kernel.org/stable/c/15f519e9f883b316d86e2bb6b767a023aafd9d83"
        }
      ],
      "title": "ceph: fix race condition validating r_parent before applying state",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39927",
    "datePublished": "2025-10-01T08:07:14.595Z",
    "dateReserved": "2025-04-16T07:20:57.147Z",
    "dateUpdated": "2026-10-21T12:37:35.623Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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